炭黑/聚氨酯熔纺导电纤维结构与性能的研究

将导电炭黑混入到热塑性聚氨酯中,经熔融纺丝制得导电纤维。随着炭黑含量增加,炭黑/聚氨酯共混体系的黏度增大,玻璃化转变温度提高。炭黑含量在13%￣16%时,炭黑在体系中的分布较为均匀,纤维的导电性能较好,力学性能可以满足应用要求。     

Improvement of Mechanical Properties of Softwood Lignin-Based Carbon Fibers

PEG-lignin fibers obtained by a solvolysis pulping of Japanese cedar with polyethylene glycol (PEG) 400 were successfully converted into defective-free, infusible fibers as a precursor for carbon fibers (CFs) by chemical curing followed by oxidative thermostabilization. The curing was performed by immersing PEG-lignin fibers in an aqueous mixed solution of hexamethylenetetramine (60 g/L) and hydrochloric acid (3 M) at 85°C for 1 h, resulting in the formation of crosslinkages between lignin molecules through methylene groups. These cured fibers were completely thermostabilized upon heating up to 250°C at a heating rate of 2°C/min under an air atmosphere. Finally, the thermostabilized fibers were carbonized to yield CFs, which showed about 1.5 times the tensile strength of our CFs previously prepared.     

Inviscid Melt Spinning of Alumina Fibers: Chemical Jet Stabilization

Alumina-calcia fibers with >50% alumina and 100% alumina fibers cannot be drawn from the melt, or conventionally melt spun, because the viscosities are too low. They can, however, be spun by inviscid melt spinning, an experimental process whereby a molten jet with a viscosity of <1 Pa.s is ejected into propane, a chemically reactive medium. The pyrolytic decomposition of propane stabilizes the molten jet. The consolidated fiber that results has a carbon-rich skin and usually, i.e., under most process conditions, but not always, a black carbon sheath. This paper identifies the chemistry and morphology of both skin and sheath by depth profile analysis, evaluates potential jet stabilization mechanisms, and concludes that the operative mechanism is rheology-dominated. Incorporation of particulate carbon in the skin of the jet increases its surface viscosity, prevents breakup into Rayleigh waves and droplets, and facilitates melt spinning of continuous filaments.     

熔纺Kraft硬木木质素基活性炭纤维的活化工艺及性能研究

以熔融纺丝制备的Kraft硬木木质素纤维(HKL)为原料,经炭化得到木质素基炭纤维(HKL-CF),再采用水蒸气活化法制备了活性炭纤维(HKL-ACF),通过红外光谱仪和扫描电镜研究了水蒸气活化对活性炭纤维化学结构和表面形貌的影响,采用全自动物理吸附仪、X射线衍射仪和拉曼光谱仪等研究了活化时间、活化温度和活化水蒸气流量对所制备活性炭纤维的比表面积、孔结构和微晶结构的影响规律。研究表明,水蒸气活化处理提高了活性炭纤维中的C—O和C＝C结构含量;随着活化时间的延长,活性炭纤维的比表面积增大,且随活化温度和水蒸气流量的提高呈现出先增大后减小的趋势;晶粒尺寸随着活化时间和温度的提高,逐渐变小,纤维表面的石墨化程度随活化时间的增加,逐渐变大;活化温度800 ℃,活化时间4 h,水蒸气流量1 mL/min下制备的活性炭纤维的BET比表面积最高可达2 081.34 m²/g,总孔容最大为1.60 cm³/g。     

Hollow Poly(3‐hydroxybutyrate) Fibers Produced by Melt Spinning

Native and nucleated PHB has been melt‐spun and the properties of the resulting fibers have been investigated. Biocompatible nucleating agents such as HAP and THY were compared to BN as a reference material. DSC was used to investigate the non‐isothermal crystallization kinetics as a function of processing temperature and cooling rate. It was found that particularly the choice of process temperature can ensure sufficient primary crystallization of native PHB: heating not higher than 10–15 K above the melting temperature induced a favorable crystallization behavior of native PHB. Thus, melt spinning at low process temperatures without additives was demonstrated to be the key to the formation of well‐defined hollow PHB fibers.

     

聚碳酸亚丙酯-聚乳酸共混熔纺纤维的制备与性能

以乙烯-马来酸酐共聚物(ZeMac)作为反应性相容剂,利用熔融纺丝法制备了聚碳酸亚丙酯(PPC)-聚乳酸(PLA)共混纤维。通过傅里叶变换红外光谱仪、热重分析仪、差示扫描量热分析仪、纤维强伸度仪等分别研究了共混纤维的分子结构、热稳定性、相容性及力学性能。结果表明:PLA的引入较大地提高了PPC的力学性能,加入少量的ZeMac可以有效地改善PPC的热稳定性,同时也能够提高共混体系的相容性。当PPC-PLA与PPC-PLA-ZeMac体系组分质量比分别为70/30和70/30/0.7时,其抗拉强度分别为11.23 MPa和20.83 MPa,较未改性的PPC分别提高了6.5倍和12.1倍,同时还能保持较高的断裂伸长率。该项研究为完全可生物降解PPC熔融共混纤维的工业化提供了可能性。     

碱处理对棉秆皮纤维木质素的影响

棉秆皮纤维中的木质素影响纤维的柔软性。采用正交实验分析碱性处理条件对棉秆皮纤维木质素的影响。实验结果表明:H2O2浓度对棉秆皮纤维的木质素影响最大,且对木质素含量的影响最显著。在NaOH质量浓度8 g/L,温度80℃,时间45min,H2O2质量浓度7 g/L条件下,棉秆皮纤维中木质素含量较少。     

Melt spinnable spandex fibers from segmented copolyetheresteraramids

Spandex fibers were obtained by melt spinning segmented copolyetheresteramides with crystallizable aromatic diamide units of uniform length and poly(tetramethyleneoxide) segments. The aramid content was varied from 3 to 22 wt %, and the molecular weight of the polyether segment ranged from 1000 to 9000 g/mol. The influence of the spinning and drawing conditions on the fiber properties was investigated. The aromatic diamide units crystallize very fast. This made the melt spinning of the polymers easy. The aramide units were also found to be very effective in increasing the modulus. For a high elasticity a low aramid content was beneficial, and with a few percent a good elastic behavior is obtained. Orientation by drawing or a spin drawing process improves the elastic behavior. The elastic properties are compared to the values of commercial spandex fibers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2194–2203, 2001     

Preparation of High-Performance Internal Tandem Electric Double-Layer Capacitors (IT-EDLCs) from Melt-Spun Lignin Fibers

Activated carbon fibers (ACFs) with large surface area were easily prepared from melt-spun fibers of polyethylene glycol lignin (PEGL). To fabricate electric double-layer capacitors (EDLCs) with a wide potential window and a high energy density in an EDLC package, electrodes (mainly composed of ACFs) were internally laminated and connected in series, in parallel, or in a series/parallel combination. Such resultant EDLCs are termed internal tandem (IT) EDLCs. As expected, the potential window was expanded by the series connection, and the capacitance was increased by the parallel connection. As a result, the energy density in the parallel-connected EDLC was remarkably increased by 66% (16.6 Wh kg^?1) compared with that of a single-cell EDLC. The EDLC with the combination connection showed both advantages. Thus, based on the package weight, the electrochemical performance of the EDLCs was remarkably improved by the IT-type lamination of electrodes.     

Characterization of Silver Particles in Silver-Containing Activated Carbon Fibers Prepared from Liquefied Wood

Silver particles in silver-containing activated carbon fibers prepared from liquefied wood were characterized by X-ray diffraction, X-ray photoelectron spectrometer, scanning electron microscope, and nitrogen adsorption isotherms. Silver irons (Ag⁺) and metallic silver (Ag⁰) were detected in fibers, and the amount of Ag⁰ was much higher than that of Ag⁺. Ag⁰ were migrated and aggregated together to form silver particles with a wide size (0–5μm), which were distributed in micropores, mesopores, and surface of fibers. The mean size of silver particles on the surface was directly related to soaking concentration, while the larger silver particles were easier to peel off from the surface. Also, the increasing micropores and mesopores were blocked by silver particles at higher concentration, and some blocked mesopores were converted into micropores. When the washing treatment was carried out, the silver particles on the surface were removed significantly, resulting in an increase in mesopore quantity. However, most of the silver particles in micropores were firmly supported. The silver-containing activated carbon fibers showed the high and lasting antibacterial activity.     

Robust PEDOT:PSS Wet‐Spun Fibers for Thermoelectric Textiles

To realize thermoelectric textiles that can convert body heat to electricity, fibers with excellent mechanical and thermoelectric properties are needed. Although poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is among the most promising organic thermoelectric materials, reports that explore its use for thermoelectric fibers are all but absent. Herein, the mechanical and thermoelectric properties of wet‐spun PEDOT:PSS fibers are reported, and their use in energy‐harvesting textiles is discussed. Wet‐spinning into sulfuric acid results in water‐stable semicrystalline fibers with a Young's modulus of up to 1.9 GPa, an electrical conductivity of 830 S cm^?1, and a thermoelectric power factor of 30 μV m^?1 K^?2. Stretching beyond the yield point as well as repeated tensile deformation and bending leave the electrical properties of these fibers almost unaffected. The mechanical robustness/durability and excellent underwater stability of semicrystalline PEDOT:PSS fibers, combined with a promising thermoelectric performance, opens up their use in practical energy‐harvesting textiles, as illustrated by an embroidered thermoelectric fabric module.     

基于超临界CO2制备熔体微分静电纺聚丙烯纤维

通过密封的压力容器将聚丙烯（PP）和超临界CO2混合,形成气固均相体系,采用熔体微分静电纺丝法制备PP和超临界CO2均相体系纤维;研究超临界CO2混合以及混合后形成的均相体系进行升温处理对制备纤维的影响。结果表明,纯PP、PP和超临界CO2混合后形成的均相体系以及对均相体系升温处理后,制备的纤维平均直径分别为12.8、8.02、5.08 μm;PP和超临界CO2混合后,聚合物的黏度得到降低;PP和超临界CO2混合后,制备的纤维结晶度得到降低。     

High-Performance Carbon Fibers Prepared by Continuous Stabilization and Carbonization of Electron Beam-Irradiated Textile Grade Polyacrylonitrile Fibers

The manufacturing of high-performance carbon fibers (CFs) from low-cost textile grade poly(acrylonitrile) (PAN) homo- and copolymers using continuous electron beam (EB) irradiation, stabilization, and carbonization on a kilogram scale is reported. The resulting CFs have tensile strengths of up to 3.1 ± 0.6 GPa and Young's moduli of up to 212 ± 9 GPa, exceeding standard grade CFs such as Toray T300. Additionally, the Weibull strength and modulus, the microstructure, and the morphology of these CFs are determined.     

熔融纺丝工艺制备碳纤维原丝

聚丙烯腈基碳纤维的制备主要采用溶液纺丝方法,生产过程需要溶剂回收,工艺流程长,因此制造成本高。笔者主要介绍了聚丙烯腈基碳纤维的制备工艺概况,特别介绍了熔融纺丝路线制备聚丙烯腈原丝的方法。利用共聚改性、增塑改性、纺丝后处理等方法,可以制备聚丙烯腈基碳纤维,并提出了由熔融纺丝制备聚丙烯腈基碳纤维的可行路线。     

Melt spun thermoresponsive shape memory fibers based on polyurethanes: Effect of drawing and heat‐setting on fiber morphology and properties

Thermoresponsive shape memory (SMP) fibers were prepared by melt spinning from a polyester polyol‐based polyurethane shape memory polymer (SMP) and were subjected to different postspinning operations to modify their structure. The effect of drawing and heat‐setting operations on the shape memory behavior, mechanical properties, and structure of the fibers was studied. In contrast to the as‐spun fibers, which were found to show low stress built up on straining to temporary shape and incomplete recovery to the permanent shape, the drawn and heat‐set fibers showed significantly higher stresses and complete recovery. The fibers drawn at a DR of 3.0 and heat‐set at 100°C gave stress values that were about 10 times higher than the as‐spun fibers at the same strain and showed complete recovery on repeated cycling. This improvement was likely due to the transformation brought about in the morphology of the permanent shape of the SMP fibers from randomly oriented weakly linked regions of hard and soft segments to the well‐segregated, oriented and strongly H‐bonded regions of hard‐segments. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2172–2182, 2007     

炭纤维增强中间相炭微球制备炭/炭复合材料

以中间相炭微球为炭源,沥青基磨切炭纤维为同质增强相,采用冷模压成型和气氛低温烧结制备出高性能炭/炭复合材料。研究了炭纤维表面处理对界面结合强度的作用机制和改善效果,分析了不同球磨时间下原始粉料的微观形貌。结果表明：炭纤维的添加有利于坯体各向均匀收缩,降低了总体积收缩率,使得复合材料密度下降;同时大幅度提升了复合材料的机械强度;添加10%（质量分数）炭纤维时弯曲强度最高,达到123.5MPa。     

Electrospun CF-PHA Nanocomposites: Effect of Surface Modifications of Carbon Fibers

Biodegradable polyhydroxyalkanoate (PHA) based polymer nanocomposite filled with nanoscale carbon fibers (CFs) were prepared by electrospinning. To enhance the processability and thermal properties of the composites, the carbon fibers were treated with chemical reagents, namely n-octanol, silane coupling agent (KH-550), and nitric acid (HNO₃). The SEM result shows that the composite fibers with nitric acid treated CFs have the finest diameters and many uniform thickness distributions. All surface treatments on carbon fibers have increased the glass transition temperatures and crystallinities of the composites, with nitric acid treatment being the best. The improvements further depended on the volume fraction of the carbon fibers.     

木材苯酚液化物碳纤维原丝的热力学性能研究

以木材苯酚液化物为原料,加入六次甲基四胺熔融纺丝后,经甲醛和盐酸溶液固化处理后得到木材液化物碳纤维原丝。利用热重分析法对原丝的热解过程及其动力学规律进行了研究。研究结果表明,原丝的最大热解速率出现在510℃,并且在748℃出现了二次热失重,最终热失重较少,热稳定性较好。在0～600℃之间木材液化物纤维存在两个明显的放热峰,且随着升温速率的增加,其放热峰向高温方向移动,放热峰的峰形也加宽变大。两个放热峰的表观活化能分别为69.36和59.02 kJ/mol;反应级数分别为0.862和0.734,且都小于1,说明两次分解反应比较复杂。     

Carbon Dioxide Regeneration of Ion Exchange Resins and Fibers: A Review

Alternative chemicals for the regenerant of ion exchangers have been the subject of research for the past sixty years. The advances spanning this time period have been significant and demonstrated at the laboratory, pilot, and commercial scale. The use of carbon dioxide as a regenerant has several significant benefits including cost savings, waste minimization, and carbon dioxide sequestration, with applications including: chemical synthesis, desalination, demineralization, metals removal and hardness removal. Having originally been pursued as a means of reducing costs of regenerant chemicals, regeneration with carbon dioxide has also been described as a non-polluting separation process and has shown significant environmental benefits. Its use as a regenerant circumvents the use of brines, strong acids, or other aggressive chemicals and with the advent of new materials such as ion exchange fibers, the list of potential applications will continue to grow. This review discusses some of the significant advances during the history of this environmentally benign regeneration process.